Title: The Obesity Code
Author: Jason Fung
Publisher: Greystone Books
Genre: Health and Wellness
First Publication: 2016
Language: English
Book Summary: The Obesity Code by Jason Fung
Everything you believe about how to lose weight is wrong. Weight gain and obesity are driven by hormones—in everyone—and only by understanding the effects of insulin and insulin resistance can we achieve lasting weight loss.
In this highly readable and provocative book, Dr. Jason Fung sets out an original, robust theory of obesity that provides startling insights into proper nutrition. In addition to his five basic steps, a set of lifelong habits that will improve your health and control your insulin levels, Dr. Fung explains how to use intermittent fasting to break the cycle of insulin resistance and reach a healthy weight—for good.
Book Review: The Obesity Code by Jason Fung
In The Obesity Code: Unlocking the Secrets of Weight Loss, Dr. Jason Fung sets out to completely reshape how we understand and treat obesity. He argues that the conventional focus on calories and willpower is misguided and doomed to fail for most people. Fung reveals how obesity is a hormonal imbalance, not a moral failing, and offers practical solutions to treat it at the root cause.
Published in 2016, The Obesity Code has challenged the mainstream views on weight loss promoted by health authorities and embraced by the public. Backed by extensive research, Fung makes a compelling case that obesity is a metabolic disorder caused by excessive insulin. He advocates intermittent fasting as a powerful tool to take control of insulin levels, reverse obesity, and spur weight loss by accessing stored body fat for fuel.
Who is Dr. Jason Fung?
To understand the perspective of The Obesity Code, it helps to begin with Dr. Fung’s background. Based in Toronto, Dr. Fung is a nephrologist who specializes in helping patients with kidney disease. Many of his patients also struggled with type 2 diabetes and obesity. Through his work, Fung realized that the standard dietary advice recommending portion control and low-fat eating was ineffective for most obese patients. This experience led him on a journey to understand the deeper causes of uncontrollable weight gain.
In studying the latest obesity science, Fung discovered insulin’s central role in fat storage. He pioneered the use of intermittent fasting as a way to lower insulin levels in his patients. The incredible results he observed solidified his conviction that obesity must be understood from a hormonal and metabolic perspective. This breakthrough research and clinical experience over the past decade informed the revolutionary arguments found in The Obesity Code.
Key Arguments of The Obesity Code
The Obesity Code begins by detailing the sheer magnitude of the obesity epidemic worldwide. Fung argues this crisis is rooted in flawed assumptions, saying “Everything we thought we knew about obesity is wrong.” He asserts that the conventional advice to restrict calories has completely failed to stop rising obesity rates.
Fung points to the futility of consciously trying to exert willpower over powerful biological drives to eat. He writes, “Hormonal imbalances, not lack of willpower, are driving the obesity epidemic.” The rest of the book explains the science behind this bold statement.
Insulin: The Root Cause of Obesity
The main premise of The Obesity Code is identifying hyperinsulinemia, or chronically high insulin levels, as the primary mechanism causing obesity. Fung explains that insulin is the main hormone responsible for fat storage. When we frequently spike insulin by eating processed carbohydrates, insulin stays elevated. In this state, the body preferentially stores calories as fat and prevents stored fat from being used for fuel.
Fung argues that mainstream authorities promote unrealistic restraint of natural food cues rather than treating the underlying insulin imbalance causing effortless weight gain. He writes, “Don’t blame the victim when the advice is bad.” The solution lies in reducing insulin levels through dietary changes, not exerting constant conscious willpower.
The Truth About Calorie Restriction Diets
Fung systematically skewers the conventional wisdom that weight is simply a matter of calories in vs. calories out. He cites major flaws in this advice, including the abysmal failure of calorie restriction to create lasting weight loss for more than a tiny minority of people.
Fung explains that the body responds to calorie restriction by lowering metabolic rate and increasing hunger hormones. This biological counter-reaction makes calorie restricted diets unsustainable for meaningful weight loss. Fung also describes research showing that macronutrient balance, not just calories, determines the hormonal effects of a diet.
Insulin’s Role in Fat Storage
Much of the book explores insulin’s role in obesity. Fung elucidates how chronically elevated insulin triggers calorie storage as fat while also making it difficult to access existing fat for energy.
He explains how eating highly processed carbohydrates spikes insulin, which then activates an enzyme called lipoprotein lipase. This enzyme enables fat to be stored in fat cells. The higher your insulin levels stay, the more fat gets trapped in cells.
Conversely, low insulin frees up stored body fat for energy expenditure via metabolism. Fung cites studies showing high insulin blocks the release of fat for fuel. So high insulin both stores and traps fat in the body.
How Fasting Lowers Insulin
The main solution Fung proposes is periodic fasting to reverse hyperinsulinemia. He reviews substantial evidence that fasting effectively lowers insulin levels by restricting calories and giving the pancreas a rest.
Lower insulin allows stored fat to be burned for energy. Beneficial hormones like growth hormone are also secreted during fasts to mobilize fat. Fung describes various intermittent fasting protocols shown to improve insulin sensitivity and aid fat burning.
Fung observes that fasting is the most time-efficient method for lowering insulin, taking hours versus the months required for calorie restriction to modestly reduce insulin. The rapid insulin reduction also minimizes hunger and metabolic slowdown.
A Review of Key Evidence
Throughout The Obesity Code, Fung cites numerous research studies to substantiate his arguments. Some of the most compelling evidence Fung presents includes:
- A year-long study where obese subjects ate only 500 calories per day but lost little weight due to slowing metabolism. This exemplifies the body’s strong counter-response to calorie restriction.
- Several studies showing insulin administration alone leads to increased fat accumulation in animals and humans, demonstrating insulin’s role promoting fat storage.
- A landmark 2004 study where people with type 2 diabetes ate either a low-fat or low-carb diet. The low-carb group reduced insulin dosage much more despite similar weight loss, showing insulin depends more on carb intake than body fat.
- Multiple studies on intermittent fasting, including Dr. Fung’s own clinical research, displaying marked improvements in insulin sensitivity, weight loss, and cardiovascular disease markers.
- Research indicating fasting increases growth hormone, which activates fat burning.
- Evidence that fasting does not slow resting metabolism or cause loss of precious muscle when limited to 24 hours or less. This allays fears around fasting.
- Examples of cultures like the Inuits that ate infrequently but maintained low body fat, illustrating that fasting does not automatically lead to weight gain due to slowed metabolism.
Key Dietary Recommendations
The Obesity Code does not prescribe one specific diet or eating pattern. However, Fung makes these main recommendations:
- Choose whole, unprocessed foods like vegetables, meat, dairy, nuts and legumes to avoid spiking insulin.
- Severely restrict sugar including juices.
- Limit overall carbohydrate intake, especially refined grains.
- Focus on anti-inflammatory whole foods.
- Eat in a compressed time window of 6-8 hours or less daily to achieve mild intermittent fasting benefits.
- Consider occasional 24+ hour fasts.
- Embrace healthy high-fat foods like olive oil and full-fat dairy, which induce low insulin secretion.
The underpinning theme is preventing prolonged, excessive insulin secretion through food choices and meal timing.
Debunking Myths
Several chapters are devoted to debunking misconceptions about obesity:
Calories In/Calories Out – Fung argues this fails because calories affect hormones, which then influence future calorie expenditure and intake. Metabolism and appetite adapt in response to calorie reduction.
Eat Less, Move More – Fung asserts this advice underestimates the biological drivers of fat gain and difficulty of sustaining discipline.
Greed and Laziness Cause Obesity – Fung maintains obesity is a hormonal imbalance, not a character flaw. He condemns vilifying individuals for a biological disorder.
Just Reduce Portions – Fung explains reducing portions of the wrong high-insulin-spiking foods provides only a minimal, transient benefit for obesity treatment.
Fung systematically dismantles each myth with logic and clinical experience. He stresses that willpower struggles arise because of fighting against the body’s hard-wired mechanisms. Effort should instead focus on inducing the body’s natural fat-burning pathways with fasting periods.
Critique
The main scientific critiques of arguments in The Obesity Code include:
- Some cite the loss of lean mass associated with intermittent fasting as detrimental and unnecessary since more gradual calorie reduction sustains muscle. Fung’s response is that mild intermittent fasting preserves muscle compared to prolonged calorie reduction. Muscle loss fears are also overblown, he argues.
- The relationship between insulin and obesity is seen as more complex and multifactorial by some researchers. However, Fung maintains that restoring insulin sensitivity is pivotal.
- Some studies dispute the metabolic advantage of ketogenic diets for weight loss. Fung’s counter is that reduced appetite and cravings make lower-carb diets easier to follow for many individuals trying to sustain weight loss.
- A few argue that insulin levels and obesity correlate only loosely in population studies. But Fung points to more rigorously controlled experiments supporting insulin’s causal metabolic effects.
While active debate continues in academia, The Obesity Code has clearly shifted perspectives among open-minded researchers. The theories are gaining increased scientific interest and followers.
Conclusion
The Obesity Code delivers an urgent wake-up call that traditional advice is failing to address the obesity crisis. Dr. Fung makes a powerful, evidence-based case that hyperinsulinemia is the root cause underlying ubiquitous weight gain in modern society. He persuasively argues that preventing excessive insulin secretion through fasting and dietary changes offers the solution.
Fung’s application of intermittent fasting has already improved health for thousands at his clinic. The Obesity Code brings his research and clinical experience to the general public. While refinements will continue, the overall insulin-focused framework represents a paradigm shift with immense potential. The Obesity Code successfully opens minds to a complementary model addressing
